Answer:
Opposite sides must be congruent.
Explanation:
Given is a picture of a quadrilateal ABCD
We have to prove that this is a parallelogram.
Recall the properties of parallelogram as
i) diagonals bisect each other
ii) opposite sides parallel
iii) opposite sides congruent
or iv) one pair of opposite sides equal and parallel
We have hence to get opposite sides congruent
So last option is right